There are four well-differentiated types of windmills, viz.:
1. The multi-bladed turbine wheel, or American type.
2. The Dutch type
3. The propeller type high-speed wheel.
4. The rotor.
According to any of the conventional windmills as listed hereinabove, the blades thereof are pivoted at the top of the tower.
And, the starting torque, and therefore the wind speed at which the wheel start, is largely determined by the blade angle. However, it is partly due to the inherently limited area of the blades to effectively be thrust by wind, and partly due to the uncertainty of operation, the conventional windmills equally generate small amount of energy. In addition, they also share the same drawback of possible interference with television reception.
It is an object of the present invention to provide an improved wind turbine whose center of gravity is low enough to attain a steady rotation thereof.
Another object of the present invention is to provide an improved wind turbine whose total area of blades is practicably large enough to make them more effectively thrust by wind.
Still another object of the present invention is to provide an improved wind turbine whose blades are liable to be ascended or descended.